Gas Supply Line Arrangements

This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 63/337,508, filed on May 2, 2022, which is incorporated by reference herein in its entirety.

The subject matter disclosed herein generally relates to methods and systems for inhibiting or removing particle contamination in a semiconductor processing chamber, and more particularly to gas supply line arrangements for inhibiting or removing particle contamination during clean and purge cycles of the process chamber.

Semiconductor substrate processing systems are used to process semiconductor substrates by techniques including etching, physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), pulsed deposition layer (PDL), plasma-enhanced pulsed deposition layer (PEPDL), and resist removal. One type of semiconductor substrate processing apparatus is a plasma processing apparatus that includes a vacuum process chamber containing upper and lower electrodes. The vacuum process chamber is supplied by process gas supply lines. In a substrate processing cycle, a radio frequency (RF) power is applied between the electrodes to excite a process gas into plasma for processing semiconductor substrates in the chamber. In cleaning and purge cycles of the process chamber, particulate material can collect on internal surfaces of the gas supply lines, contaminate a wafer in subsequent processing, and cause leakage of valves, for example.

The background description provided herein is to generally present the context of the disclosure. It should be noted that the information described in this section is presented to provide the skilled artisan some context for the following disclosed subject matter and should not be considered as admitted prior art. More specifically, work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Methods, systems, and computer programs are presented for inhibiting or removing particle contamination in a semiconductor processing chamber and apparatus. Some examples include gas supply line arrangements for inhibiting particle contamination during clean and purge cycles of the processing chamber.

In some examples, a gas supply line arrangement is provided for inhibiting particle contamination in a substrate process chamber. An example gas supply line arrangement comprises a cleaning gas source for a clean cycle of the substrate process chamber; a purge gas source for a purge cycle of the substrate process chamber; a gas supply line to carry cleaning gas and purge gas towards the substrate process chamber; and a three-port valve comprising: a valve inlet connected to the gas supply line; a first valve outlet in fluid communication with the substrate process chamber, the first valve outlet operable to admit or prevent a passage of cleaning gas to the substrate process chamber; and a second valve outlet connected to a divert line and operable to admit or prevent a passage of particle-containing purge gas to the divert line.

In some examples, the second valve outlet is configured only to be opened when the first valve outlet is closed.

In some examples, the first valve outlet defines an internal cleaning gas termination point when closed.

In some examples, the second valve outlet defines an internal purge gas diversion point when opened.

In some examples, the internal purge gas diversion point is upstream of the internal cleaning gas termination point within a body of the three-port valve.

In some examples, a volume of the body of the three-port valve between the purge gas diversion point and the cleaning gas termination point is purgeable of gas and particulate material during the purge cycle.

In some examples, the three-port valve is directly connected to the substrate process chamber or an inlet manifold thereof.

Example methods, systems, and computer programs are directed to methods, systems, and machine-readable storage media for inhibiting or removing particle contamination during process cycles in a semiconductor processing chamber. Some examples include gas supply line arrangements for inhibiting particle contamination during clean and purge cycles of the processing chamber. Unless explicitly stated otherwise, components and functions are optional and may be combined or subdivided, and operations may vary in sequence or be combined or subdivided. In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of example embodiments. It will be evident to one skilled in the art, however, that the present subject matter may be practiced without these specific details.

As used herein, the terms “wafer” and “substrate” are used interchangeably. A wafer or substrate indicates a support material upon which, or within which, elements of a semiconductor device are fabricated or attached. A substrate (e.g., substratein) may include, for example, wafers (e.g., having a diameter of 100 mm, 150 mm, 200 mm, 300 mm, 950 mm, or larger) composed of, for example, elemental-semiconductor materials (e.g., silicon (Si) or germanium (Ge)) or compound-semiconductor materials (e.g., silicon germanium (SiGe) or gallium arsenide (GaAs)). Additionally, other substrates include, for example, dielectric materials such as quartz or sapphire (onto which semiconductor materials may be applied). Example substrates include blanket substrates and patterned substrates. A blanket substrate is a substrate that includes a low-surface (or planar) top surface. A patterned substrate is a substrate that includes a high-surface (or structured) top surface. A structured top surface of a substrate may include different high-surface-area structures such as 3D NAND memory holes or other structures.

A general description of a process chamber using the disclosed methods is provided with reference to.illustrates a process chamber(e.g., an etching or deposition chamber) for manufacturing substrates, according to one embodiment. In some examples, the process chambermay also be referred to as a vacuum chamber. Exciting an electric field between two electrodes is one of the methods to obtain radio frequency (RF) gas discharge in a process chamber. When an oscillating voltage is applied between the electrodes, the discharge obtained is referred to as a CCP discharge.

Plasmamay be created within a processing zoneof the process chamber, utilizing one or more process gases to obtain a wide variety of chemically reactive by-products created by the dissociation of the various molecules caused by electron-neutral collisions. The chemical aspect of etching involves the reaction of the neutral gas molecules and their dissociated by-products with the molecules of the to-be-etched surface and producing volatile molecules, which may be pumped away. When a plasma is created, the positive ions are accelerated from the plasma across a space-charge sheath separating the plasma from chamber walls to strike the substrate surface with enough energy to remove material from the substrate surface. The process of using highly energetic and chemically reactive ions to selectively and anisotropically remove materials from a substrate surface is called Reactive Ion Etch (RIE). In some examples, the process chambermay be used in connection with PECVD or PEALD deposition processes.

A controllermanages the operation of the process chamber, such as during processing, clean and purge cycles, and by controlling the different elements in the process chamber, such as RF generator, gas source(s), and gas pump. The gas source(s)may include a cleaning gas source and a purge gas source, described further below. In one embodiment, fluorocarbon gases, such as CFand CF, are used in a dielectric etch process for their anisotropic and selective etching capabilities; but the principles described herein may be applied to other plasma-creating gases. The fluorocarbon gases are readily dissociated into chemically reactive by-products that include smaller molecular and atomic radicals. These chemically reactive by-products etch away the dielectric material.

The process chamberillustrates a processing chamber with an upper (or top) electrodeand a lower (or bottom) electrode. The upper electrodemay be grounded or coupled to an RF generator (not shown), and the lower electrodeis coupled to the RF generatorvia a matching network. The RF generatorprovides an RF signal between the upper electrodeand the lower electrodeto generate RF power in one or multiple (e.g., two or three) different RF frequencies. According to the desired configuration of the process chamberfor a particular operation, at least one of the multiple RF frequencies may be turned ON or OFF. In the embodiment shown in, the RF generatoris configured to provide at least three different frequencies, e.g., 400 kHz, 2 MHz, 27 MHz, and 60 MHz, but other frequencies are also possible.

The process chamberincludes a gas showerhead on the upper electrodeto input process gas into the process chamberprovided by the gas source(s), and a perforated confinement ringthat allows the gas to be pumped out of the process chamberby gas pump. In some example embodiments, the gas pumpis a turbomolecular pump, but other types of gas pumps may be utilized.

When the substrateis present in the process chamber, the silicon focus ringis situated next to substratesuch that there is a uniform RF field at the bottom surface of the plasmafor uniform etching (or deposition) on the surface of the substrate. The embodiment ofshows a triode reactor configuration where the upper electrodeis surrounded by a ground electrode(e.g., a symmetric RF ground electrode). Insulatoris a dielectric that isolates the ground electrodefrom the upper electrode. Other implementations of the process chamber, including ICP-based implementations, are also possible without changing the scope of the disclosed embodiments.

Each frequency generated by the RF generatormay be selected for a specific purpose in the substrate manufacturing process. In the example of, with RF powers provided at 400 kHz, 2 MHz, 27 MHz, and 60 MHz, the 400 kHz or 2 MHz RF power provides ion energy control, and the 27 MHz and 60 MHz powers provide control of the plasma density and the dissociation patterns of the chemistry. This configuration, where each RF power may be turned ON or OFF, enables certain processes that use ultra-low ion energy on the substrates, and certain processes (e.g., soft etch for low-k materials) where the ion energy has to be low (e.g., under 700 or 200 eV).

In another embodiment, a 60 MHz RF power is used on the upper electrodeto get ultra-low energies and very high density. This configuration allows chamber cleaning with high-density plasma when substrateis not in the process chamber, while minimizing sputtering on the Electrostatic Chuck Surface (ESC). The ESC surface is exposed when substrateis not present, and any ion energy on the surface should be avoided, which is why the bottom 2 MHz and 27 MHz power supplies may be off during cleaning.

In an example embodiment, the process chamberfurther includes a sensorwhich may be placed between the matching networkof the RF generatorand the lower electrode. The sensormay include a voltage-current (or V-I) sensor configured to generate a plurality of signals (e.g., sensed data) that are indicative of at least one signal characteristic of RF signals generated by the RF generatorat a corresponding plurality of time instances. For example, the V-I sensor may generate a plurality of signals that are indicative of one or more of the following signal characteristics of RF signals: voltage, current, phase, delivered power, and impedance. In some examples, the plurality of signals generated by the sensorat the corresponding plurality of time instances may be stored (e.g., in on-chip memory of controlleror the sensor) and later retrieved (e.g., by the controller) for subsequent processing. In other aspects, the plurality of signals generated by the sensor, at the corresponding plurality of time instances, may be automatically communicated to the controlleras they are generated.

In some examples, the gas source(s)are connected to one or more gas line supply arrangements disposed upstream of the gas showerhead on the upper electrode. The gas supply line arrangements may include one or more inlet manifolds (not visible in) connected to the process chamber. As mentioned above, the gas source(s)may include a cleaning gas source and a purge gas source. In some examples, the gas line supply arrangements are connected to these gas sources and are used for cleaning and purge cycles of the process chamberbetween or after substrate processing cycles. In this regard, an inlet manifold may carry a plasma gas containing fluorine for chamber cleaning in a “clean cycle”. The “clean cycle” is sometimes followed by a “purge cycle” using argon gas to remove aluminum fluoride particles generated during the clean cycle. The aluminon fluoride particulate material can collect on internal surfaces of the gas supply lines, contaminate a wafer in subsequent processing, and cause leakage of ALD valves, for example.

In conventional gas line supply arrangements, for example as shown in, a remote plasma generator (for a clean cycle) or gas source (for a purge cycle) can be isolated from the process chamberof, using a two-port valve. Here, argon purge gas containing aluminum fluoride particles is exhausted directly to the process chamberand can cause the wafer-contamination problem discussed above. Other processing cycles can be affected by such particulate matter. Examples in this disclosure seeks to inhibit particle contamination in wafer processing, chamber cleaning, and purge cycles, and in some cases provide particle removal and decontamination during or in preparation for such cycles.

Some further conventional examples seek to divert the argon purge away from the process chamber, for example as shown in. Here, the two-port valveofcan be closed, disallowing particles to flow into the process chamber. During a purge cycle, the particle-containing argon gas instead flows in a diverted purge paththrough another two-port valveinto a divert line. A gas diversion pointlies externally of and upstream of the two-port valvesandat a joint or fork in the gas supply line, as shown. A gas termination pointin the gas supply linelies at the downstream two-port valve. This non-coincident arrangement of external gas diversion and termination points can create a dead zone(or volume) between the gas diversion pointand the gas termination point. The existence of the dead zonedoes not solve, and in fact can exacerbate, the problem of particle contamination. Particles can still be trapped in the dead zoneineven when a purge cycle is underway. These particles are unable to escape down the divert line. The only way out of the dead zonedownstream is through the process chamber. Thus, when the two-port valveis opened again for subsequent wafer processing or cleaning these trapped particles pass directly into the process chamberleading to the same problems discussed further above. Thus, despite provision of a divert line, the contamination issue persists.

In some present examples of this disclosure, these problems are addressed by gas supply line arrangements for a process chamberthat include a strategically placed and configured three-port valve. The three-port valve is also known as a three-way valve in some examples.

With reference to, in some examples a three-port valveis located at the gas diversion pointof, or at least at the start of a purge pathin a gas supply line arrangement of a process chamber. The purge pathproceeds through the three-port valvebut not through any portion of a downstream line below the three-port valvethat might otherwise form a dead zone.

As described more fully below, the gas diversion pointand the gas termination pointofare rendered substantially coincident in the three-port valveof. In some examples, the gas diversion pointand the gas termination pointare rendered substantially coincident within the body of the three-port valve. The external dead zoneis substantially eliminated or at least minimized, accordingly. In some examples described further below, to the extent a minimized dead zone remains inside the three-port valve, this zone nevertheless remains purgeable of particulate material and contamination.

In some examples, the three-port valveis located immediately adjacent a process chamberor inlet manifold thereof such that no dead zonedownstream of the three-port valveis formed in a supply line. In other words, the gas supply lineterminates at the three-port valveand does not pass beyond it.

An example three-port valveis shown in schematic outline in. The three-port valvehas a valve inlet, a first valve outlet, and a second valve outlet, hence the name three-port or three-way valve. First and second pneumatically powered valve actuatorsandoperate to open and close the first and second valve outletsand, respectively.

shows example modes of a three-port valve. In a first mode(e.g., “plasma flow” mode) of the three-port valve, for example, adopted during substrate processing or chamber cleaning gas, such as fluorine, enters the valve inletof the three-port valve. The inlet gas may be provided for example from an upstream gas source from gas source(s)ofor a remote plasma gas generator (RPC generator). The first valve outletis open and allows passage of the fluorine gas to be admitted into the downstream process chamberfor cleaning or substrate processing purposes. The second valve outletis closed and there is no gas flow through that outlet in the first plasma flow mode. All gas flow is constrained to pass into the process chamber. However, the abrasive and corrosive nature of a fluorine gas used in a cleaning cycle can still generate unwanted particles, such as aluminum fluoride particles, that can collect on internal surfaces of gas lines and chamber walls and cause wafer contamination and valve leakage.

Thus, in a second mode(e.g., “purge flow” mode), a purge gas such as argon is used to purge these particles away and inhibit wafer contamination and other damage occurring in the chamber and associated valves and equipment. In an example present arrangement, instead of flushing the trapped dead zone particles into the chamber as in the prior art, the first valve outletis closed, disallowing entry of gas and particles into the chamber, as shown by “no flow”. The second valve outletis opened and the purged gas and particles exit the valve through that outlet and pass harmlessly atinto a divert line at. In some examples, the second valve outletis configured only to be opened when the first valve outletis closed, so that the risk of allowing particles and contamination into the process chamberofis reduced, if not eliminated.

In a third mode(e.g., “no flow” mode), there is no flow of gas through the three-port valveas both of the first and second valve outletsandare closed. In this mode, particulate material or contamination can be held temporarily and safely upstream of the three-port valve, a divert line, or the process chamber, as needed.

Internal configurations of an example three-port valvecorresponding to the three modes including the first mode(plasma flow), the second mode(purge flow), and the third mode(no flow) can be seen with reference toof the accompanying drawings.

In modes 1 and 2, a gas such as fluorine or argon (or a mixed gas containing either or different constituents) can be admitted into the three-port valvevia the valve inletin a plane orthogonal to the page. In mode 1 (for example including a clean cycle), the first valve outletis open and the admitted gas can pass into the chamberfor chamber cleaning in a fluorine-plasma path. In mode 1, the second valve outletis connected to a divert (purge) line but is closed, as shown. No gas passes into the divert line in mode 1.

In mode 2 (for example including a purge cycle), argon gas is supplied into the valve inlet, again orthogonally into the page. The first valve outletis closed and defines a gas termination pointdisposed internally of the three-port valve. No purge gas and, perhaps more importantly, no particle contamination carried by the purge gas, is allowed to be admitted to the chamberin mode 2. Instead, the second valve outletis opened allowing the purge gas and the particle contamination carried therein to pass harmlessly into the connected divert line. The second valve outletdefines a gas diversion point.

In the illustrated example, the gas diversion pointis disposed slightly upstream of the gas termination point, but nevertheless is still provided internally of the three-port valve. In the illustrated example, the gas termination pointand the gas diversion pointare not disposed upstream or downstream in external or separate gas lines, for example as configured in the prior art discussed above. Rather, as in the illustrated example, the gas termination pointand gas diversion pointare substantially coincident (proximate to each other without an intervening supply line), or at least coincident in the sense that they are both disposed within the body of the same three-port valve. The existence of a dead zone is substantially eliminated, or at least eliminated with respect to the external environment of the three-port valveand the surrounding gas supply line arrangement. Of additional note is that to the extent a potential dead zone or volume exists internally of the three-port valvebetween the gas termination pointand the gas diversion point, as shown for example by the hatched area marked; this zone remains flushable. As purge gas passes through the three-port valveit cleans or sweeps the potential dead zoneout and entrains particulate material and other contamination out through the second valve outletin a purge pathas shown.

In mode 3 (no flow), both the first valve outletand the second valve outletof the three-port valveare closed. No gas is admitted to the chamberor to the divert line.

Some examples include methods. With reference to, a methodof inhibiting particle contamination during a clean or purge cycle of a substrate process chamber comprises: at operation, providing a cleaning gas source for a clean cycle of the substrate process chamber; at operation, providing a purge gas source for a purge cycle of the substrate process chamber; at operation, connecting a gas supply line to carry cleaning gas and purge gas towards the substrate process chamber; at operation, connecting a three-port valve into a gas supply line arrangement for the substrate process chamber, the three-port valve comprising a valve inlet connectable to the gas supply line; a first valve outlet in fluid communication with the substrate process chamber, the first valve outlet operable to admit or prevent a passage of the cleaning gas to the substrate process chamber, the three-port valve further comprising a second valve outlet connectable to a divert line and operable to admit or prevent a passage of particle-containing purge gas to the divert line; at operation, connecting the three-port valve to the divert line; and, at operation, discharging the particle-containing purge gas into the divert line during the purge cycle.

In some examples, the methodfurther comprises opening the second valve outlet only when the first valve outlet is closed.

In some examples, the methodfurther comprises configuring the first valve outlet to define an internal cleaning gas termination point when closed.

In some examples, the methodfurther comprises configuring the second valve outlet to define an internal purge gas diversion point when opened.

In some examples, the methodfurther comprises configuring or operating the three-port valve such that the internal purge gas diversion point is upstream of the internal cleaning gas termination point within a body of the three-port valve.

In some examples, the methodfurther comprises purging a volume of the body of the three-port valve between the internal purge gas diversion point and the internal cleaning gas termination point of gas and particulate material during the purge cycle.

In some examples, the methodfurther comprises connecting the three-port valve directly connected to the substrate process chamber or an inlet manifold thereof.

Some examples provide a non-transitory machine-readable medium including instructions which, when read by a machine, cause the machine to perform operations in a method of inhibiting particle contamination during a clean or purge cycle of a substrate process chamber, the method comprising: opening or closing a cleaning gas source for a clean cycle of the process chamber; opening or closing a purge gas source for a purge cycle of the process chamber; controlling a connected gas supply line carrying cleaning gas and purge gas towards the substrate process chamber; controlling actuators of a three-port valve connected to the gas supply line, the three-port valve comprising: a valve inlet in fluid communication with the gas supply line; a first valve outlet in fluid communication with the substrate process chamber, the first valve outlet operable to admit or prevent a passage of the cleaning gas to the substrate process chamber, the three-port valve further comprising a second valve outlet connectable to a divert line and operable to admit or prevent a passage of particle-containing purge gas to the divert line; and sending a signal to one of the actuators of the three-port valve to open the second valve outlet to discharge the particle-containing purge gas into the divert line during the purge cycle.

is a block diagram illustrating an example of a machine(such as the controllerof) upon or by which one or more example process embodiments described herein may be implemented or controlled. In alternative embodiments, the machinemay operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machinemay operate in the capacity of a server machine, a client machine, or both in server-client network environments. In an example, the machinemay act as a peer machine in a peer-to-peer (P2P) (or other distributed) network environment. Further, while only a single machineis illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as via cloud computing, software as a service (SaaS), or other computer cluster configurations.

Examples, as described herein, may include, or may operate by, logic, several components, or mechanisms. Circuitry is a collection of circuits implemented in tangible entities that include hardware (e.g., simple circuits, gates, logic). Circuitry membership may be flexible over time and underlying hardware variability. Circuitries include members that may, alone or in combination, perform specified operations when in use. In one example, the hardware of the circuitry may be immutably designed to carry out a specific operation (e.g., hardwired). In another example, the hardware of the circuitry may include variably connected physical components, (e.g., execution units, transistors, simple circuits) including a computer-readable medium physically modified (e.g., magnetically and electrically by the moveable placement of invariant massed particles) to encode instructions of the specific operation. In connecting the physical components, the underlying electrical properties of a hardware constituent are changed (for example, from an insulator to a conductor or vice versa). The instructions enable embedded hardware (e.g., the execution units or a loading mechanism) to create members of the circuitry in hardware via the variable connections to carry out portions of the specific operation when in operation. Accordingly, the computer-readable medium is communicatively coupled to the other components of the circuitry when the device is operating. In some examples, any of the physical components may be used in more than one member of more than one circuitry. For example, under operation, execution units may be used in a first circuit of a first circuitry at one point in time and reused by a second circuit in the first circuitry, or by a third circuit in a second circuitry, at a different time.

The machine (e.g., computer system)may include a hardware processor(e.g., a central processing unit (CPU), a hardware processor core, or any combination thereof), a graphics processing unit (GPU), a main memory, and a static memory, some or all of which may communicate with each other via an interlink (e.g., bus). The machinemay further include a display device, an alphanumeric input device(e.g., a keyboard), and a user interface (UI) navigation device(e.g., a mouse). In an example, the display device, alphanumeric input device, and UI navigation devicemay be a touch screen display. The machinemay additionally include a mass storage device (e.g., drive unit), a signal generation device(e.g., a speaker), a network interface device, and one or more sensors, such as a Global Positioning System (GPS) sensor, compass, accelerometer, or another sensor. The machinemay include an output controller, such as a serial (e.g., Universal Serial Bus (USB)), parallel, or other wired or wireless (e.g., Infrared (IR), Near Field Communication (NFC)) connection to communicate with or control one or more peripheral devices (e.g., a printer, card reader).